Abstract: Nrf2 Regulation of Ductal Pancreatic Cancer Etiology and Treatment We seek to leverage the unique capability of Pancreatic Ductal Adenocarcinoma (PDA) cells to resist oxidative stress towards the development of effective therapies for this malignancy. Indeed, in addition to the advanced stage of disease that patients typically have at presentation, the lethality of PDA largely reflects the poor response of their tumors to systemic therapeutics. We previously reported that PDA initiation in a mouse model required the Nrf2 transcription factor, in part through the ability of Nrf2 to direct the expression of many genes that collectively reduce intracellular reactive oxygen species (ROS). Additional work by others demonstrated that somatic mutations in NRF2 or its binding protein KEAP1 occur commonly in lung and breast cancer, resulting in the activation of the NRF2 pathway and increased drug resistance. To determine how Nrf2 promotes cancer formation and therapeutic resistance in PDA we have generated new conditional models and developed mouse and human pancreatic cancer organoid cultures. The new mouse models and organoids will serve two complementary purposes: to unequivocally determine whether Nrf2 functions solely in a cell intrinsic manner in promoting PDA, and as model systems to discover the Nrf2 effector pathways and explore new therapeutic strategies in vivo and ex vivo (Aim 1). Accordingly, we have found that Nrf2 regulates protein translation through its antioxidant function to promote cell proliferation in PDA organoids, and we will define the biochemical mechanisms involved and determine whether they represent new therapeutic opportunities (Aim 2). Furthermore, we have identified new, non-antioxidant related Nrf2 target genes in PDA organoids, and we will determine their role in PDA pathogenesis (Aim 3). Our project will utilize bespoke model systems and state-of-the-art mass spectrometric, genomic, transcriptomic, and bioinformatics methods in order to identify new mediators of Nrf2 function in PDA. Nrf2 effector pathways and target genes discovered in our work will be assessed for their individual importance in PDA biology and therapeutic resistance, and the most promising candidates will be validated in organoid and mouse models using genetic and pharmacological approaches. We anticipate that our results will explain fundamental aspects of oncogenesis in PDA and will lead to the development of more effective therapies for this deadly malignancy.